no 



Step of this ladder, and this is common to all ani- 

 mals. Man himself, lordly as he is at his perfect 

 growth, is not only the most helpless at his birth, 

 but continues so longer than any other member of 

 the animal world. However, except that of growth, 

 he undergoes no considerable alteration in this life. 



Quadrupeds undergo a greater change yearly; by 

 *the loss and renovation of their outward covering. 

 This change however is gradual, and almost insensible, 

 the latter being of the same substance, and even co- 

 lour as the former. But there is an exception to this 

 in those which undergo this change twice in the year 

 as do the bears, hares and foxes in Greenland, and 

 Other extremely cold countries: and the ermins, which 

 are frequent in Yorkshire, and several other parts of 

 England, their hair changes white at the approach 

 of winter, and in spring assumes its former colour. 



One class however of viviparous animals undergo 

 a more sudden alteration, namely, the serpent-kind. 

 These having no hair or fur to lose gradually, cast 

 their whole covering at once, and are so dexterous 

 therein, though they have neither feet nor claws, that 

 itheir whoje skins are frequently fo un d entire, without 

 even the cornea or outward case of the eyes, which 

 accompanies the other exuviae, being broken. 



Next to these are oviparous animals. These make 

 their first appearance in a state of entire inaction, but 

 being gradually ripened by natural or artiGcial heat, 

 burst out, some in their complete state, as lizards, spi. 

 ders, and fish in general, and others as birds, requir- 

 ing like viviparous animals, the addition of the ex- 

 trementitious parts. Almost all the species of these 

 which we know, need the same farther change with 

 the viviparous. All birds moult their feathers, and 

 many in cold countries change the colour of them in 

 the winter. Lizards drop their skins like s-nakes ^ 

 one kind of th^m, water newts, every two or three 

 weeks. Spiders, crabs, and ail whose outward cover, 

 ing is crustaceous, and therefore incapable of dis- 

 tension, cast their -shells oace a year, at which tim,e 



